GC.RegisterForFullGCNotification(Int32, Int32) Metodo

public:
 static void RegisterForFullGCNotification(int maxGenerationThreshold, int largeObjectHeapThreshold);

public static void RegisterForFullGCNotification (int maxGenerationThreshold, int largeObjectHeapThreshold);

[System.Security.SecurityCritical]
public static void RegisterForFullGCNotification (int maxGenerationThreshold, int largeObjectHeapThreshold);

static member RegisterForFullGCNotification : int * int -> unit

[<System.Security.SecurityCritical>]
static member RegisterForFullGCNotification : int * int -> unit

Public Shared Sub RegisterForFullGCNotification (maxGenerationThreshold As Integer, largeObjectHeapThreshold As Integer)

Parametri

Attributi

SecurityCriticalAttribute

Eccezioni

Esempio

Nell'esempio seguente viene illustrato come registrare una notifica di Garbage Collection e avviare un thread per monitorare lo stato della notifica di Garbage Collection. Questo esempio di codice fa parte di un esempio più ampio fornito per l'argomento Notifiche di Garbage Collection .

using namespace System;
using namespace System::Collections::Generic;
using namespace System::Threading;

namespace GCNotify
{
    ref class Program
    {
    private:
        // Variable for continual checking in the
        // While loop in the WaitForFullGCProc method.
        static bool checkForNotify = false;

        // Variable for suspending work
        // (such servicing allocated server requests)
        // after a notification is received and then
        // resuming allocation after inducing a garbage collection.
        static bool bAllocate = false;

        // Variable for ending the example.
        static bool finalExit = false;

        // Collection for objects that
        // simulate the server request workload.
        static List<array<Byte>^>^ load = gcnew List<array<Byte>^>();


    public:
        static void Main()
        {
            try
            {
                // Register for a notification.
                GC::RegisterForFullGCNotification(10, 10);
                Console::WriteLine("Registered for GC notification.");

                checkForNotify = true;
                bAllocate = true;

                // Start a thread using WaitForFullGCProc.
                Thread^ thWaitForFullGC = gcnew Thread(gcnew ThreadStart(&WaitForFullGCProc));
                thWaitForFullGC->Start();

                // While the thread is checking for notifications in
                // WaitForFullGCProc, create objects to simulate a server workload.
                try
                {
                    int lastCollCount = 0;
                    int newCollCount = 0;


                    while (true)
                    {
                        if (bAllocate)
                        {
                            load->Add(gcnew array<Byte>(1000));
                            newCollCount = GC::CollectionCount(2);
                            if (newCollCount != lastCollCount)
                            {
                                // Show collection count when it increases:
                                Console::WriteLine("Gen 2 collection count: {0}", GC::CollectionCount(2).ToString());
                                lastCollCount = newCollCount;
                            }

                            // For ending the example (arbitrary).
                            if (newCollCount == 500)
                            {
                                finalExit = true;
                                checkForNotify = false;
                                break;
                            }
                        }
                    }

                }
                catch (OutOfMemoryException^)
                {
                    Console::WriteLine("Out of memory.");
                }


                finalExit = true;
                checkForNotify = false;
                GC::CancelFullGCNotification();

            }
            catch (InvalidOperationException^ invalidOp)
            {

                Console::WriteLine("GC Notifications are not supported while concurrent GC is enabled.\n"
                    + invalidOp->Message);
            }
        }

    public:
        static void OnFullGCApproachNotify()
        {
            Console::WriteLine("Redirecting requests.");

            // Method that tells the request queuing
            // server to not direct requests to this server.
            RedirectRequests();

            // Method that provides time to
            // finish processing pending requests.
            FinishExistingRequests();

            // This is a good time to induce a GC collection
            // because the runtime will induce a full GC soon.
            // To be very careful, you can check precede with a
            // check of the GC.GCCollectionCount to make sure
            // a full GC did not already occur since last notified.
            GC::Collect();
            Console::WriteLine("Induced a collection.");

        }


    public:
        static void OnFullGCCompleteEndNotify()
        {
            // Method that informs the request queuing server
            // that this server is ready to accept requests again.
            AcceptRequests();
            Console::WriteLine("Accepting requests again.");
        }

    public:
        static void WaitForFullGCProc()
        {
            while (true)
            {
                // CheckForNotify is set to true and false in Main.
                while (checkForNotify)
                {
                    // Check for a notification of an approaching collection.
                    GCNotificationStatus s = GC::WaitForFullGCApproach();
                    if (s == GCNotificationStatus::Succeeded)
                    {
                        Console::WriteLine("GC Notifiction raised.");
                        OnFullGCApproachNotify();
                    }
                    else if (s == GCNotificationStatus::Canceled)
                    {
                        Console::WriteLine("GC Notification cancelled.");
                        break;
                    }
                    else
                    {
                        // This can occur if a timeout period
                        // is specified for WaitForFullGCApproach(Timeout)
                        // or WaitForFullGCComplete(Timeout)
                        // and the time out period has elapsed.
                        Console::WriteLine("GC Notification not applicable.");
                        break;
                    }

                    // Check for a notification of a completed collection.
                    s = GC::WaitForFullGCComplete();
                    if (s == GCNotificationStatus::Succeeded)
                    {
                        Console::WriteLine("GC Notification raised.");
                        OnFullGCCompleteEndNotify();
                    }
                    else if (s == GCNotificationStatus::Canceled)
                    {
                        Console::WriteLine("GC Notification cancelled.");
                        break;
                    }
                    else
                    {
                        // Could be a time out.
                        Console::WriteLine("GC Notification not applicable.");
                        break;
                    }
                }


                Thread::Sleep(500);
                // FinalExit is set to true right before
                // the main thread cancelled notification.
                if (finalExit)
                {
                    break;
                }
            }
        }

    private:
        static void RedirectRequests()
        {
            // Code that sends requests
            // to other servers.

            // Suspend work.
            bAllocate = false;

        }

        static void FinishExistingRequests()
        {
            // Code that waits a period of time
            // for pending requests to finish.

            // Clear the simulated workload.
            load->Clear();

        }

        static void AcceptRequests()
        {
            // Code that resumes processing
            // requests on this server.

            // Resume work.
            bAllocate = true;
        }
    };
}

int main()
{
    GCNotify::Program::Main();
}

using System;
using System.Collections.Generic;
using System.Threading;

namespace GCNotify
{
    class Program
    {
        // Variable for continual checking in the
        // While loop in the WaitForFullGCProc method.
        static bool checkForNotify = false;

        // Variable for suspending work
        // (such servicing allocated server requests)
        // after a notification is received and then
        // resuming allocation after inducing a garbage collection.
        static bool bAllocate = false;

        // Variable for ending the example.
        static bool finalExit = false;

        // Collection for objects that
        // simulate the server request workload.
        static List<byte[]> load = new List<byte[]>();

        public static void Main(string[] args)
        {
            try
            {
                // Register for a notification.
                GC.RegisterForFullGCNotification(10, 10);
                Console.WriteLine("Registered for GC notification.");

                checkForNotify = true;
                bAllocate = true;

                // Start a thread using WaitForFullGCProc.
                Thread thWaitForFullGC = new Thread(new ThreadStart(WaitForFullGCProc));
                thWaitForFullGC.Start();

                // While the thread is checking for notifications in
                // WaitForFullGCProc, create objects to simulate a server workload.
                try
                {

                    int lastCollCount = 0;
                    int newCollCount = 0;

                    while (true)
                    {
                        if (bAllocate)
                        {
                            load.Add(new byte[1000]);
                            newCollCount = GC.CollectionCount(2);
                            if (newCollCount != lastCollCount)
                            {
                                // Show collection count when it increases:
                                Console.WriteLine("Gen 2 collection count: {0}", GC.CollectionCount(2).ToString());
                                lastCollCount = newCollCount;
                            }

                            // For ending the example (arbitrary).
                            if (newCollCount == 500)
                            {
                                finalExit = true;
                                checkForNotify = false;
                                break;
                            }
                        }
                    }
                }
                catch (OutOfMemoryException)
                {
                    Console.WriteLine("Out of memory.");
                }

                finalExit = true;
                checkForNotify = false;
                GC.CancelFullGCNotification();
            }
            catch (InvalidOperationException invalidOp)
            {

                Console.WriteLine("GC Notifications are not supported while concurrent GC is enabled.\n"
                    + invalidOp.Message);
            }
        }

        public static void OnFullGCApproachNotify()
        {

            Console.WriteLine("Redirecting requests.");

            // Method that tells the request queuing
            // server to not direct requests to this server.
            RedirectRequests();

            // Method that provides time to
            // finish processing pending requests.
            FinishExistingRequests();

            // This is a good time to induce a GC collection
            // because the runtime will induce a full GC soon.
            // To be very careful, you can check precede with a
            // check of the GC.GCCollectionCount to make sure
            // a full GC did not already occur since last notified.
            GC.Collect();
            Console.WriteLine("Induced a collection.");
        }

        public static void OnFullGCCompleteEndNotify()
        {
            // Method that informs the request queuing server
            // that this server is ready to accept requests again.
            AcceptRequests();
            Console.WriteLine("Accepting requests again.");
        }

        public static void WaitForFullGCProc()
        {
            while (true)
            {
                // CheckForNotify is set to true and false in Main.
                while (checkForNotify)
                {
                    // Check for a notification of an approaching collection.
                    GCNotificationStatus s = GC.WaitForFullGCApproach();
                    if (s == GCNotificationStatus.Succeeded)
                    {
                        Console.WriteLine("GC Notification raised.");
                        OnFullGCApproachNotify();
                    }
                    else if (s == GCNotificationStatus.Canceled)
                    {
                        Console.WriteLine("GC Notification cancelled.");
                        break;
                    }
                    else
                    {
                        // This can occur if a timeout period
                        // is specified for WaitForFullGCApproach(Timeout)
                        // or WaitForFullGCComplete(Timeout)
                        // and the time out period has elapsed.
                        Console.WriteLine("GC Notification not applicable.");
                        break;
                    }

                    // Check for a notification of a completed collection.
                    GCNotificationStatus status = GC.WaitForFullGCComplete();
                    if (status == GCNotificationStatus.Succeeded)
                    {
                        Console.WriteLine("GC Notification raised.");
                        OnFullGCCompleteEndNotify();
                    }
                    else if (status == GCNotificationStatus.Canceled)
                    {
                        Console.WriteLine("GC Notification cancelled.");
                        break;
                    }
                    else
                    {
                        // Could be a time out.
                        Console.WriteLine("GC Notification not applicable.");
                        break;
                    }
                }

                Thread.Sleep(500);
                // FinalExit is set to true right before
                // the main thread cancelled notification.
                if (finalExit)
                {
                    break;
                }
            }
        }

        private static void RedirectRequests()
        {
            // Code that sends requests
            // to other servers.

            // Suspend work.
            bAllocate = false;
        }

        private static void FinishExistingRequests()
        {
            // Code that waits a period of time
            // for pending requests to finish.

            // Clear the simulated workload.
            load.Clear();
        }

        private static void AcceptRequests()
        {
            // Code that resumes processing
            // requests on this server.

            // Resume work.
            bAllocate = true;
        }
    }
}

open System
open System.Threading

// Variable for continual checking in the
// While loop in the WaitForFullGCProc method.
let mutable checkForNotify = false

// Variable for suspending work
// (such servicing allocated server requests)
// after a notification is received and then
// resuming allocation after inducing a garbage collection.
let mutable bAllocate = false

// Variable for ending the example.
let mutable finalExit = false

// Collection for objects that simulate the server request workload.
let load = ResizeArray<byte []>()


let redirectRequests () =
    // Code that sends requests
    // to other servers.

    // Suspend work.
    bAllocate <- false

let finishExistingRequests () =
    // Code that waits a period of time
    // for pending requests to finish.

    // Clear the simulated workload.
    load.Clear()

let acceptRequests () =
    // Code that resumes processing
    // requests on this server.

    // Resume work.
    bAllocate <- true

let onFullGCApproachNotify () =
    printfn "Redirecting requests."

    // Method that tells the request queuing
    // server to not direct requests to this server.
    redirectRequests ()

    // Method that provides time to
    // finish processing pending requests.
    finishExistingRequests ()

    // This is a good time to induce a GC collection
    // because the runtime will induce a full GC soon.
    // To be very careful, you can check precede with a
    // check of the GC.GCCollectionCount to make sure
    // a full GC did not already occur since last notified.
    GC.Collect()
    printfn "Induced a collection."


let onFullGCCompleteEndNotify () =
    // Method that informs the request queuing server
    // that this server is ready to accept requests again.
    acceptRequests ()
    printfn "Accepting requests again."

let waitForFullGCProc () =
    let mutable broken = false

    while not broken do
        let mutable broken = false
        // CheckForNotify is set to true and false in Main.
        while checkForNotify && not broken do
            // Check for a notification of an approaching collection.
            match GC.WaitForFullGCApproach() with
            | GCNotificationStatus.Succeeded ->
                printfn "GC Notification raised."
                onFullGCApproachNotify ()
                // Check for a notification of a completed collection.
                match GC.WaitForFullGCComplete() with
                | GCNotificationStatus.Succeeded ->
                    printfn "GC Notification raised."
                    onFullGCCompleteEndNotify ()
                | GCNotificationStatus.Canceled ->
                    printfn "GC Notification cancelled."
                    broken <- true
                | _ ->
                    // Could be a time out.
                    printfn "GC Notification not applicable."
                    broken <- true
            | GCNotificationStatus.Canceled ->
                printfn "GC Notification cancelled."
                broken <- true
            | _ ->
                // This can occur if a timeout period
                // is specified for WaitForFullGCApproach(Timeout)
                // or WaitForFullGCComplete(Timeout)
                // and the time out period has elapsed.
                printfn "GC Notification not applicable."
                broken <- true

        Thread.Sleep 500
        // FinalExit is set to true right before
        // the main thread cancelled notification.
        if finalExit then broken <- true



try
    // Register for a notification.
    GC.RegisterForFullGCNotification(10, 10)
    printfn "Registered for GC notification."

    checkForNotify <- true
    bAllocate <- true

    // Start a thread using WaitForFullGCProc.
    let thWaitForFullGC = Thread(ThreadStart waitForFullGCProc)
    thWaitForFullGC.Start()

    // While the thread is checking for notifications in
    // WaitForFullGCProc, create objects to simulate a server workload.
    try
        let mutable lastCollCount = 0
        let mutable newCollCount = 0

        let mutable broken = false

        while not broken do
            if bAllocate then
                load.Add(Array.zeroCreate<byte> 1000)
                newCollCount <- GC.CollectionCount 2

                if newCollCount <> lastCollCount then
                    // Show collection count when it increases:
                    printfn $"Gen 2 collection count: {GC.CollectionCount(2)}"
                    lastCollCount <- newCollCount
                // For ending the example (arbitrary).
                if newCollCount = 500 then
                    finalExit <- true
                    checkForNotify <- false
                    broken <- true
    with :? OutOfMemoryException -> printfn "Out of memory."

    finalExit <- true
    checkForNotify <- false
    GC.CancelFullGCNotification()
with :? InvalidOperationException as invalidOp ->
    printfn $"GC Notifications are not supported while concurrent GC is enabled.\n{invalidOp.Message}"

Imports System.Collections.Generic
Imports System.Threading

Class Program
    ' Variables for continual checking in the
    ' While loop in the WaitForFullGcProc method.
    Private Shared checkForNotify As Boolean = False

    ' Variable for suspending work 
    ' (such as servicing allocated server requests)
    ' after a notification is received and then 
    ' resuming allocation after inducing a garbage collection.
    Private Shared bAllocate As Boolean = False

    ' Variable for ending the example.
    Private Shared finalExit As Boolean = False

    ' Collection for objects that  
    ' simulate the server request workload.
    Private Shared load As New List(Of Byte())


    Public Shared Sub Main(ByVal args() As String)
        Try
            ' Register for a notification. 
            GC.RegisterForFullGCNotification(10, 10)
            Console.WriteLine("Registered for GC notification.")

            bAllocate = True
            checkForNotify = True

            ' Start a thread using WaitForFullGCProc.
            Dim thWaitForFullGC As Thread = _
                New Thread(New ThreadStart(AddressOf WaitForFullGCProc))
            thWaitForFullGC.Start()

            ' While the thread is checking for notifications in
            ' WaitForFullGCProc, create objects to simulate a server workload.
            Try
                Dim lastCollCount As Integer = 0
                Dim newCollCount As Integer = 0
                
                
                While (True)
                    If bAllocate = True Then

                        load.Add(New Byte(1000) {})
                        newCollCount = GC.CollectionCount(2)
                        If (newCollCount <> lastCollCount) Then
                            ' Show collection count when it increases:
                            Console.WriteLine("Gen 2 collection count: {0}", _
                                              GC.CollectionCount(2).ToString)
                            lastCollCount = newCollCount
                        End If

                        ' For ending the example (arbitrary).
                        If newCollCount = 500 Then
                            finalExit = True
                            checkForNotify = False
                            bAllocate = False
                            Exit While
                        End If

                    End If
                End While
                
            Catch outofMem As OutOfMemoryException
                Console.WriteLine("Out of memory.")
            End Try

            finalExit = True
            checkForNotify = False
            GC.CancelFullGCNotification()

        Catch invalidOp As InvalidOperationException
            Console.WriteLine("GC Notifications are not supported while concurrent GC is enabled." _
                              & vbLf & invalidOp.Message)
        End Try
    End Sub

    Public Shared Sub OnFullGCApproachNotify()
        Console.WriteLine("Redirecting requests.")

        ' Method that tells the request queuing  
        ' server to not direct requests to this server. 
        RedirectRequests()

        ' Method that provides time to 
        ' finish processing pending requests. 
        FinishExistingRequests()

        ' This is a good time to induce a GC collection
        ' because the runtime will induce a ful GC soon.
        ' To be very careful, you can check precede with a
        ' check of the GC.GCCollectionCount to make sure
        ' a full GC did not already occur since last notified.
        GC.Collect()
        Console.WriteLine("Induced a collection.")
    End Sub

    Public Shared Sub OnFullGCCompleteEndNotify()
        ' Method that informs the request queuing server
        ' that this server is ready to accept requests again.
        AcceptRequests()
        Console.WriteLine("Accepting requests again.")
    End Sub

    Public Shared Sub WaitForFullGCProc()

        While True
            ' CheckForNotify is set to true and false in Main.

            While checkForNotify
                ' Check for a notification of an approaching collection.
                Dim s As GCNotificationStatus = GC.WaitForFullGCApproach
                If (s = GCNotificationStatus.Succeeded) Then
                    Console.WriteLine("GC Notification raised.")
                    OnFullGCApproachNotify()
                ElseIf (s = GCNotificationStatus.Canceled) Then
                    Console.WriteLine("GC Notification cancelled.")
                    Exit While
                Else
                    ' This can occur if a timeout period
                    ' is specified for WaitForFullGCApproach(Timeout) 
                    ' or WaitForFullGCComplete(Timeout)  
                    ' and the time out period has elapsed. 
                    Console.WriteLine("GC Notification not applicable.")
                    Exit While
                End If

                ' Check for a notification of a completed collection.
                s = GC.WaitForFullGCComplete
                If (s = GCNotificationStatus.Succeeded) Then
                    Console.WriteLine("GC Notifiction raised.")
                    OnFullGCCompleteEndNotify()
                ElseIf (s = GCNotificationStatus.Canceled) Then
                    Console.WriteLine("GC Notification cancelled.")
                    Exit While
                Else
                    ' Could be a time out.
                    Console.WriteLine("GC Notification not applicable.")
                    Exit While
                End If

            End While
            Thread.Sleep(500)
            ' FinalExit is set to true right before  
            ' the main thread cancelled notification.
            If finalExit Then
                Exit While
            End If

        End While
    End Sub

    Private Shared Sub RedirectRequests()
        ' Code that sends requests
        ' to other servers.

        ' Suspend work.
        bAllocate = False
    End Sub

    Private Shared Sub FinishExistingRequests()
        ' Code that waits a period of time
        ' for pending requests to finish.

        ' Clear the simulated workload.
        load.Clear()

    End Sub

    Private Shared Sub AcceptRequests()
        ' Code that resumes processing
        ' requests on this server.

        ' Resume work.
        bAllocate = True
    End Sub
End Class

Commenti

Per ogni generazione, Il Garbage Collector imposta una soglia per le allocazioni in tale generazione. Quando le dimensioni delle allocazioni superano questa soglia, viene attivata un'operazione di Garbage Collection in tale generazione. Ad esempio, se la soglia di generazione 2 è di 20 MB (il che significa che 20 MB sopravvive alle raccolte di generazione 1 e viene promossa alla generazione 2) e più di 20 MB sono sopravvissuti alla generazione 1 e viene richiesto di generare la generazione 2, la successiva operazione di Garbage Collection verrà tentata come raccolta di generazione 2. Analogamente, se la soglia dell'heap di oggetti di grandi dimensioni (LOH) è pari a 20 MB e l'app ha allocato più di 20 MB di oggetti di grandi dimensioni, la successiva Operazione di Garbage Collection verrà tentata anche come raccolta di generazione 2 (poiché loH viene raccolto solo in Garbage Collection di seconda generazione).

Le maxGenerationThreshold soglie e largeObjectHeapThreshold controllano quanto in anticipo si riceve una notifica prima che si verifichi un'operazione di Garbage Collection completa. Maggiore è la soglia, maggiore è il numero di allocazioni che possono verificarsi tra la notifica e la successiva Garbage Collection completa successiva.

Se si verificano situazioni in cui un'operazione di Garbage Collection completa da Common Language Runtime influisce negativamente sulle prestazioni dell'applicazione, è possibile chiedere di ricevere una notifica quando il runtime sta per eseguire un'operazione completa di Garbage Collection e aggirare tale raccolta inducendo manualmente una raccolta (usando il Collect metodo ) quando le condizioni sono ancora favorevoli. Oltre a modificare manualmente la pianificazione di Garbage Collection, la notifica GC completa è utile negli scenari seguenti:

• Si monitora l'approccio di un'operazione di Garbage Collection completa e, quando si riceve una notifica che si avvicina, si riducono le dimensioni dei dati in tempo reale, ad esempio rilasciando alcune voci della cache. Di conseguenza, quando si verifica l'operazione di Garbage Collection, è in grado di recuperare più memoria.

• È possibile monitorare il completamento di un'operazione di Garbage Collection completa in modo da poter raccogliere alcune statistiche. Ad esempio, è possibile misurare le dimensioni dell'heap al completamento GC in modo da conoscere le dimensioni dei dati in tempo reale. Dopo un GC completo, l'heap ha le dimensioni più piccole.

Per altre informazioni su ciò che rappresenta un'operazione completa di Garbage Collection, vedere Notifiche di Garbage Collection.

Quando si esegue la registrazione per una notifica di Garbage Collection, è possibile ricevere una notifica quando si avvicina un'operazione completa di Garbage Collection e al termine. Questo modello è simile al modo in cui il sistema operativo monitora le notifiche di memoria insufficiente.

Usare le linee guida seguenti per specificare i maxGenerationThreshold parametri e largeObjectHeapThreshold :

• Maggiore è il valore soglia, maggiore sarà il numero di allocazioni tra la notifica e l'operazione di Garbage Collection completa.

  Un valore soglia maggiore offre più opportunità per il runtime di verificare la presenza di una raccolta che si avvicina. Ciò aumenta la probabilità che si riceverà una notifica. Tuttavia, non è consigliabile impostare la soglia troppo elevata perché comporta un numero maggiore di allocazioni prima che il runtime induca la raccolta successiva.

  Quando si induce manualmente una raccolta al momento della notifica usando un valore soglia elevato, vengono recuperati meno oggetti rispetto a quelli recuperati dalla raccolta successiva del runtime.

• Minore è il valore soglia, minore è l'allocazione tra la notifica e l'intera Garbage Collection.

Si applica a

Vedi anche

• Notifiche di Garbage Collection